Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa

Day, J.P., Wang, S.M., Allan, A.K., Kean, L., Davies, S.A. , Gray, J.V. and Dow, J.A.T. (2008) Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa. Journal of Cell Science, 121(15), pp. 2612-2619. (doi:10.1242/jcs.033084)

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Abstract

The vital task of vectorial solute transport is often energised by a plasma membrane, proton-motive V-ATPase. However, its proposed partner, an apical alkali-metal/proton exchanger, has remained elusive. Here, both FlyAtlas microarray data and in situ analyses demonstrate that the bacterial kefB and kefC (members of the CPA2 family) homologues in Drosophila, CG10806 and CG31052, respectively, are both co-expressed with V-ATPase genes in transporting epithelia. Immunocytochemistry localises endogenous CG10806 and CG31052 to the apical plasma membrane of the Malpighian (renal) tubule. YFP-tagged CG10806 and CG31052 both localise to the plasma membrane of Drosophila S2 cells, and when driven in principal cells of the Malpighian tubule, they localise specifically to the apical plasma membrane. V-ATPase-energised fluid secretion is affected by overexpression of CG10806, but not CG31052; in the former case, overexpression causes higher basal rates, but lower stimulated rates, of fluid secretion compared with parental controls. Overexpression also impacts levels of secreted Na+ and K+. Both genes rescue exchanger-deficient (nha1 nhx1) yeast, but act differently; CG10806 is driven predominantly to the plasma membrane and confers protection against excess K+, whereas CG31052 is expressed predominantly on the vacuolar membrane and protects against excess Na+. Thus, both CG10806 and CG31052 are functionally members of the CPA2 gene family, colocalise to the same apical membrane as the plasma membrane V-ATPase and show distinct ion specificities, as expected for the Wieczorek exchanger

Item Type:Articles
Keywords:Drosophila melanogaster, ion transport, integrative physiology, functional genomics
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Gray, Dr Joseph and Dow, Professor Julian and Day, Dr Jonathan and Davies, Professor Shireen
Authors: Day, J.P., Wang, S.M., Allan, A.K., Kean, L., Davies, S.A., Gray, J.V., and Dow, J.A.T.
Subjects:Q Science > QH Natural history > QH301 Biology
Q Science > QH Natural history > QH426 Genetics
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
College of Medical Veterinary and Life Sciences > School of Life Sciences
Journal Name:Journal of Cell Science
Publisher:The Company of Biologists Ltd
ISSN:0021-9533
ISSN (Online):1477-9137
Published Online:15 July 2008

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
378481Exploration of cyclic 3', 5' guanosine monophosphate (cGMP) signalling dynamics in vivoShireen DaviesBiotechnology and Biological Sciences Research Council (BBSRC)BB/C000633/1Institute of Molecular Cell and Systems Biology
438341Analysis of the structure, function and regulation of the Rho1-specific GTP exchange proteins in the yeast call wall integrity pathwayJoseph GrayBiotechnology and Biological Sciences Research Council (BBSRC)BB/E011632/1LS - BIOMOLECULAR SCIENCE